Radar images show enlargement of summit eruptive vent

This animated GIF shows a sequence of radar amplitude images that were acquired by the Italian Space Agency's Cosmo-SkyMed satellite system. The series shows changes to the caldera area of Kīlauea Volcano that occurred over May 5 at 6:12 a.m. HST, May 17 at 6:12 a.m. HST, and May 21 at 6:12 a.m. HST. The satellite transmits a radar signal at the surface and measures the strength of the reflection, with bright areas indicating a strong reflection and dark areas a weak reflection. Strong reflections indicate rough surfaces or slopes that point back at the radar, while weak reflections come from smooth surfaces or slopes angled away from the radar.

The May 5 image was acquired before any small explosions occurred from the summit. The May 17 and 21 images show changes to the summit area after the onset of small explosions and ash emissions. Major changes over time include: (1) a darkening of the terrain south of Halema‘uma‘u, which reflects accumulation of ash; (2) enlargement of the summit eruptive vent on the floor of Halema‘uma‘u; and (3) the development of a subsiding area on the east rim of Halema‘uma‘u that reflects slumping of a portion of the rim towards the growing collapse pit on the crater floor.